The invention relates to rotational indexing of a crankshaft in an internal combustion engine to facilitate test and repair adjustments requiring precise indexing of rotational degrees of the crankshaft.
The invention particularly arose from a need to provide precise indexing on marine diesel engines subject to heavy usage, which requires frequent and periodic valve clearance adjustment. Diesel engines raise the particular problem of a high compression ratio pressure head to be overcome in torquing or rotating the engine through precise small scale indexed angular degrees. This problem is further amplified in those applications where the mechanic may wish to not relieve compression pressure in any of the cylinders by removing a glow plug or the like, to avoid the necessity of installing a new gasket and resealing such broken seal. In such applications, the high pressure head which must be overcome in minutely rotationally indexing the crankshaft presents problems as to preciseness and exactness.
In previous diesel engines and the like, extended bolts were provided on the crankshaft pulley, and a pry bar was used thereacross to rotate the engine. In another prior method, the starter motor is used to rotate the engine. None of these prior systems satisfies the need to accurately rotate the engine for precise indexing of rotational degrees of the crankshaft to facilitate test and repair adjustments. The present invention addresses and solves this problem in a particularly simple and efficient manner.